Released
Product Bulletin No.: TDS-03-13
Top Drive Drilling System
Date: March 28, 2003
To:
Product:
Affected
Assemblies:
Objective:
All Operators of TDS -9SA and TDS -11SA Top Drive Drilling Systems
TDS-9SA and -11SA Top Drive Systems
Hydraulic Motor/ Shot Pin Assemblies (P/N 30151875-500 and -504)
To Advise the Users of Rotating Link Adapter Motor/Shot Pin Retrofit Kits
Problem:
Varco is aware of some isolated field performance issues with the Hydraulic Drive/ Shot Pin
Assembly currently used on TDS-9SA and TDS -11SA Top Drive Drilling Systems. These
problems have included reports of sluggish and intermittent rotation of the rotating link adapter,
occasionally resulting in the inability to engage the shot pin, thus preventing the clamp cylinder
from clamping on the drill pipe. Other problems have included leakage and cracked mounting
flanges on the hydraulic drive motor and broken dowel pins.
Solution:
The TDS-9SA and TDS -11SA utilize a Hydraulic Drive/Shot Pin Assembly with the capability of
remote positioning of the drill pipe elevator. The major components of the Hydraulic Drive/Shot
Pin Assembly are the hydraulic drive/shot pin’s housing, compound gear, hydraulic motor, drive
gear and the shot pin.
The Hydraulic Drive/Shot Pin Assembly drives the compound gear, which meshes with the link
adapter gear, and provides torque to rotate the link adapter, links, elevator and drill pipe.
Although these performance reports have been isolated, Varco has evaluated the design and
revised the assembly to provide additional rotational torque.
The RLA Motor/Shot Pin Retrofit Kit (P/N 30157763) includes an improved Hydraulic
Drive/Shot Pin Assembly. The assembly consists of an increased capacity hydraulic motor,
which is rated at 50% higher pressure than the system pressure that it will be subjected to,
making it capable of working under very severe conditions. The new gear train is robust with a
higher gear ratio capable of providing twice the torque compared to the assembly it is replacing.
Please contact your local Varco Service Center for price and availability or if you have any questions regarding
this product bulletin.
2002 Varco All Rights Reserved
TDS-03-13
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